HP 8340A Service Manual page 35

7. Using a logic probe or DVM, probe the output pins of the device being tested. Verify that the
output pins are set as shown in Table 8A-5b.
[-] [2] [1] [8] [ 4] [6] [ H z].
8. Press
This key sequence reverses the state of the output pins set in step 6. This verifies that the pins
can be set to both TTL levels.
Using a logic probe or DVM, probe the output pins of tlie device being tested. Verify that the
9.
output pins are set as shown in Table 8A-5c.
Data Line
Decimal Value
Data Line
Decimal Value
Data Line
Bit Level
0 Level Typically <0.3V
y
1 Level Typicall
Data Line
Bit Level
0 Level Typically < 0.3V
1 Level Typically
DAC VERIFICATION
The DACs which can be tested using Direct 1/0 Addressing are those which have a strobe listed
in Table 8A-4 and the data bus connected to them. An example of one of these DACs is A54Ul5.
Several other DACs have their data sent from an output register (eg. A54U6). These DACs may
be tested in the same manner as described below but all the addressing and data entry must be to
the output register. The equipment required is a DVM. The procedure is as follows:
Verify the operation of the DAC's 1/0 Strobe as described in the strobe verifi c ation
1.
procedure.
2. Press
[ INSTR PRESET ] [MANUAL ].
frequency range (eg. A27Ul 0, frequencies
tested, enter the appropriate MANUAL frequency.
[ SHIFT] [ GH z ]
3. Press
This key sequence sets up the 1/0 Strobe Subchannel. Enter the desired Subchannel number
where the xx is located.
8-34
Model 8340A - Service
Table Direct 1/0 Data Bit Information
8A-5.
a. Decimal Values for Set Data Bits.
15 14
-32768 16384
7 6
12 8 64
b.
Bit Configuration for 21845 Entry.
15 14 13 12
0 1 1
0
3.0V
>
c. Bit Configuration for -21846 Entry.
15 14 13 12
1 0 0
1
3.0V
>
xx [ Hz ] .
Scans by HB9HCA and HB9FSX
13 12
11
8192 4096 2048
5 4 3
32 16 8
11 10
9 8 7 6
0
1 0 1 0 1
11 10
9 8 7 6
1 0
1 0 1 0
A few of the DACs only operate over a specifi c
20
GHz). If this is the case for the DAC being
>
10 9 8
512
1024 256
2 1 0
4 2 1
5 4 3 2 1 0
0 1 0 1 0 1
5 4 3 2 1 0
1 0 1 0 1 0